Quick reference: what wire gauge do you need for a given amperage? Based on NEC Table 310.16, with the 60°C and 75°C columns shown separately because the termination rating decides which one applies.
| Amps | Cu 60°C | Cu 75°C | Al 60°C | Al 75°C | Common Use |
|---|---|---|---|---|---|
| 15A | 14 AWG | 14 AWG | 12 AWG | 12 AWG | Standard lighting and outlet circuits |
| 20A | 12 AWG | 12 AWG | 10 AWG | 10 AWG | Kitchen, bathroom, garage circuits |
| 30A | 10 AWG | 10 AWG | 8 AWG | 8 AWG | Dryers, water heaters, small AC units |
| 40A | 8 AWG | 8 AWG | 6 AWG | 8 AWG | Electric ranges, large AC units |
| 50A | 6 AWG | 8 AWG | 4 AWG | 6 AWG | Ranges, hot tubs, EV chargers, sub-panels |
| 60A | 4 AWG | 6 AWG | 3 AWG | 4 AWG | Sub-panels, large EV chargers, heavy equipment |
| 70A | 4 AWG | 4 AWG | 2 AWG | 3 AWG | Large sub-panels, commercial equipment |
| 80A | 3 AWG | 4 AWG | 1 AWG | 2 AWG | Large sub-panels, industrial feeders |
| 100A* | 1 AWG | 3 AWG | 1/0 AWG | 1 AWG | Main panels, large sub-panels, service entrance |
| 125A* | — | 1 AWG | — | 2/0 AWG | Service entrance, large main panels |
| 150A* | — | 1/0 AWG | — | 3/0 AWG | Service entrance, commercial panels |
| 200A* | — | 3/0 AWG | — | 250 kcmil | Residential service entrance, commercial feeders |
The table shows two temperature columns for each conductor material: 60°C and 75°C. Which column applies depends on the insulation type and the termination (breaker/lug) rating:
When in doubt, use the 60°C column. It is the more conservative choice and is required for the most common residential wiring method (NM-B cable).
60°C column: required for NM-B cable and, by default, for circuits of 100A or less (NEC 110.14(C)). 75°C column: THHN/THWN-2 with breakers and lugs rated 75°C, and all circuits over 100A. NEC 240.4(D) is applied (14/12/10 AWG copper max 15/20/30A). * A one-family dwelling service or main feeder may be sized at 83% under NEC 310.12: 100A 4 AWG Cu / 2 AWG Al, 150A 1 AWG Cu / 2/0 Al, 200A 2/0 Cu / 4/0 Al.
A 30-amp circuit needs 10 AWG copper or 8 AWG aluminum under NEC Table 310.16. NEC 240.4(D) caps 10 AWG copper at 30A, so it is the minimum in either temperature column. Common uses include electric dryers, water heaters and small air conditioners.
A 50-amp circuit needs 6 AWG copper or 4 AWG aluminum at 60°C (required for NM-B cable), or 8 AWG copper or 6 AWG aluminum with THHN and 75°C-rated terminations. Common uses: electric ranges, hot tubs, Level 2 EV chargers and sub-panels.
A 100-amp feeder or sub-panel needs 1 AWG copper or 1/0 aluminum at 60°C, or 3 AWG copper or 1 AWG aluminum with 75°C-rated terminations. A 100-amp dwelling service sized under NEC 310.12 can use 4 AWG copper or 2 AWG aluminum.